Nitrosocarbamates and method of controlling fungi, bacteria and insects



ire

This application is a continuation in part of my copendin application Serial No. 556,104, filed December 29, 1955, and now abandoned, which is a continuation in part of my application Serial No. 433,791, filed June 1, 1954, now abandoned.

My invention relates to fungicidal, bactericidal, and insecticidal compounds and to a method for their application.

A number of pesticides which act primarily in the vapor phase, such as formaldehyde, methyl bromide, bromine, ethylene dichloride, paradichlorobenzene, nitrogen trichloride, diphenyl and chloropicrin, have been used for various preservative purposes, and are useful and of value in controlling molds, bacteria and insect pests. My present invention provides the art with a further means whereby fungi and bacteria, and in one embodiment also insects and their larvae, can be efiectively controlled by means of a vapor phase treatment or process.

In accordance with my present invention, material normally subject to fungus and bacterial attack, e.g., fruits such as apples, peaches, oranges and bananas, and freshly harvested farm crops such as hay, grain, seed and corn, is preserved by introducing into an atrnospheresurrounding the material an amount effective to prevent such attack of at least one nitrosocarbamate having the general for mula R is an alkyl radical having from 1 to 12 carbon atoms States atgnt 2.;

or monochloroalkyl radical having from 2 to 12 carbon atoms. Typical R radicals, therefore, include methyl. ethyl, propyl, butyl, etc.; and chloroethyl, chloro-propyl, etc., Representative nitrosocarbamates include methyl N-nitroso-N-methylcarbamate, butyl N-nitroso-N-methylcarbamate, amyl N-nitrosoN-methylcarbamate, hexyl N- nitr-osoN-methylcarbamate, n-octyl N-nitroso-N-methylcarbamate, Z-ethylhexyl N-nitroso-N-methylcarbamate, n-decyl N-nitroso-N-methylcarbamate, dodecyl N-nitroso- N-methyl-carbamate, Z-chloroethyl N-nitroso-N-methylcarbamate, and 3 chloro-n-propyl N-nitroso-N-methylcarbamate.

Of the compounds falling Within the scope of the generic formula just stated, I have found that the compounds wherein R is n-butyl, n-amyl or n-hexyl, that is n-butyl, N-nitroso-N-methylcarbamate, n-amyl N-nitroso-N-mcthylcarbamate and n-hexyl N-nitroso-N-methylcarbamate, respectively, are outstanding from the standpoint of their effectiveness or high bactericidal and fungicidal activity. Thus, these compounds, which have not heretofore been prepared to the best of my knowledge, exhibit an activity approaching that of mercurial compounds, which are among the most highly active fungicides and bactericide known to the art.

Patented Nov. 21 1961 The chemical compounds employed in accordance with my invention are not generally new. Some of them have previously been prepared and the remainder can be prepared utilizing procedures which are .known in the art. Thus, methyl N-nitroso-N-methylcarbamate can be prepared as follows:

An aqueous solution containing two moles of methylamine is first prepared and into this solution is gradually run with good stirring one mole of methyl chlorocarbonate (methyl chloroformate). The solution now contains one mole of the compound CH NHCOOCH the methyl ester of methylcarbamic acid, and one mole of methylamine hydrochloride. The next step is to convert the methyl ester of methylcarbamic acid to methyl N-nitroso-N-methylcarbamate. This is done by adding one mole of hydrochloric or one-half mole of sulfuric acid and then adding slowly one mole of aqueous sodium nitrite, the mixture being kept cool. The methyl N-nitroso-N-rnethylcarbamate separates from the solution as anoil'and settles at the bottom of the reaction vessel, fromwhich it can be run off directly. The product can be dried by allowing it to stand in contact with a drying material, such as anhydrous magnesium sulfate. The following reactions are involved:

The normal butyl ester of N iiitroso-N-methyl carbamic acid can be prepared as follows: 124 grams of a 25% by weight aqueous solution of monomethylamine is admixed with 100 ml. of water and the mixture is then placed-in an ice bath. With good stirring and cooling, 68.29 grams of n-butyl chlorocarbonate is added gradually. .Thereafter, 45 ml. of 37% by .weight hydrochloric acid (commercial concentrated hydrochloricacid) is added slowly, after which an aqueous solution of 35 grams of sodium nitrite dissolved in ml. of water is added. The product separates as apink oil, and is separated and dried with magnesium sulfate. Other alkyl nitroso carbamic acid esters can beprepared by reacting the proper monoa-lkyl amine and alkyl chlorocarbonate, and nitrosating the reaction product of the two.

These chemicals provide a new and effective means for sterilizing surfaces simply by placing the materials to be sterilized in an atmosphere in which a small amount of the chemical or mixture of chemicals is allowed to vaporize. The chemicals can be used in a number of ways in which pesticides have heretofore been used in the art, for example, as aerosols, in impregnated paper, in impregnated powders, in solution in various solvents, and so forth, to provide an environment in which the chemicals are present.

As mentioned above, one embodiment of. my invention provides means whereby not only fungi and bacteria can be efiectivelycontrolled by vapor phas'e'treatment but also insects and their :l-arvae can be controlled by the vapor phase treatment. Thus, in practicing this embodiment of the present invention, nitrosocarbamates falling within the scope of the formula RN.(N0) COOR wherein R is an alkyl radical having a number of carbon atoms, n, from 1 to 4, and R is an alkyl radical having a number of carbon atoms, n, from Ho 2, or mixtures of such compounds in the vapor phase, are applied to articles, such as garments and fabrics, or to enclosed spaces, such as closets, to control insect pests. Of the compounds 4 Table II falling within the scope of the generic formula just stated, G m dust con- Percent seeds showing it has been found that those wherein the sum of 2n'+n is 5 ilf f gg gfi Y growth equal to at least 5 are outstanding from the standpoint methylearof their effectiveness and high activity against insects and bumflte Bacteria their larvae. For example, where R is methyl and R is n-propyl or n-butyl, or where R is ethyl and R is g .8 3 methyl or ethyl the compounds so described have superior 2. 5 0 0 rti 1 4.5 0 prope es. 0.1 22 0 The following examples illustrate the practice of my mventlon: Gm. dust con- EXAMPLE I taining n-amyl 1 N-nitroso-N- In testing various compounds employed within the 0 11161711171021"- bamate scope of my invention for fungicidal and bacter1c1dal activity, the following test procedure was used. Measured 10 O O quantities of an acetone solution of the compound were 5 0 0 put on filter paper in the top of a Petri dish. The aceg 8 tone was then allowed to evaporate, evaporation taking 41 0 place in several minutes. Mycophil agar was poured into the bottom of the Petri dish and, after hardening, the agar o dust conwas inoculated. The bottom of the Petri dish was then -nitros0-N- inverted so that the 1noculated agar was directly above 2 methylcarthe filter paper containing the toxicant, the filter paper 5 bamate not touching the agar. The plates were then incubated in this position for 96 hours at C.12 C. and ob- 8 served. Table I :below sets forth results obtained using 2.5 is 0 this test procedure. The test organisms used were Bacil- 30 a g lus subtilis, Staphylococcus aureus, Escherichia coli, and Aspergillus niger.

Table l Bactericidal, p.p.m. needed Bacteriostatic, p.p.m. needed Fungi- Fungito kill to prevent growth oidal, static, p.p.m. p.p.m. CH3N(NO)COOR needed needed to kill to B. S. E. coli B. S. E. 0021' A. niyer prevent subtilis (ZHTCZLS .subtilis uureus growth A.m'ger +85 42 +85 +85 42 +85 *8. 5 s. 5 42 8.5 42 42 8.5 0.8 8.5 4.2 +42 +42 42 s. 5 42 0.8 8.5 4. 2 +85 85 s5 s5 s5 42 42 4.2 4.2 0.85 42 4.2 0.16 8.5 *4.2 0.3 4. 2 85 +85 4. 2 42 a5 4. 2 85 8.5 3.5 42 8.5 4.2 0.8 0.8 yl 42 42 4.2 8.5 8.5 0.16 8.5 4.2 Ethyl N -11itroso-N-ethylcarbamate 42 8. 5 85 42 4. 2 85 85 85 NorE.--In the above table, the asterisk indicates bacterial contamination. The parts per million are parts per million of compound in the vapor phase, as determined by the amount of compound used and the volume of the Petri dish.

EXAMPLE II In this test, 100 grams of wheat seed was placed in a jar and various amounts of compound added. When added, the compound was in the form of a dust, that is, the compound was in admixture with clay in a weight ratio of 6:94. The jar was then tumbled for fifteen minutes, after which the seeds were placed on Mycophil agar and observed for evidence of growth of microorganisms. Table II below sets forth the results obtained when this test was performed. An untreated control showed 100% bacterial and fungicidal contamination.

carbamate, 5 p.p.m.; isobutyl N-nitroso-N-methylcarbamate, 20 p.p.m.; n-amyl N-nitroso-N-methylcarbamate, 5 p.p.m.; and n-hexyl N-nitroso-N-methylcarbamate,

The results of the tests are presented in the following table.

p.p.m.

EXAMPLE HI 5 Piplmhinsec Percent hillggrgt end of 72 tieide (based Tests were conducted in l2-litre round-bottomed on air balloon flasks fitted with aluminum foil-covered cork -vo1ume) filfigfi 3553: stoppers. The toxicant to be tested, n-butyl N-nitroso-N- methylcarbamate was weighed into an aluminum foil cup 83 100 100 and introduced into the flask. The atmosphere of the 10 100 0 flask was stirred by means of an aluminum foil vane or propeller attached to a paper clip and driven by an external magnetic drive. Test insects, clothes moth larvae EXAMPLE VI 7 and carpet beetles Were Placed on Standard test wool The procedure described in Example Ill was carried cloth dusted with brewers yeast and the whole was placed t using as h i i id h l N- i N h 1 in 150 X millimeter glass Culture tubes- Each tube carbamate with the same controls as in Example III. was pp with? Piece of fine mfish Silk hinting 010th, The results of the tests are presented in the following held in place with a rubber band. The silk bolting cloth bl permitted a ready entry of the vapor and discouraged the escape of the test insects capable of climbing the glass 20 walls. The culture tubes containing the test insects were P p m msw Percent 33 end hung in the central portion of the flask from the cork maid '(p stopper by a suspending thread. With the culture tubes 61 22 Clothes Carpet 1n place and the stopper firmly inserted, the flask was moth larvae beetles gently warmed on a steam bath just until the toxicant had 25 been vaporized. The atmosphere in the flask was then agitated by propelling the stirring vane with the magnetic 2-3 igg 18g stirrer. In one of the balloon flasks the amount of toxicant was suflicient to produce a concentration of 8.3 parts per million based on the air volume. In another the EXAMPLE 11 oncentration was 4.2 .m. In a control flask, aradidhlorobenzene was use h and in another control fi sk, no Into tlghfly Sealed te.st.clcsets there were placed Open insecticide was added. After a period of 72 hours followglass mceptacles cemammg copfused flour beetles ing initiation of the test the percentage kin was deter r clothes moth larvae, as well as inoculated plates of fungi minei The results, which represent an average of a 30 and bacteria. There were also placed Ill the closets number of tests in each case, are presented in the follow- Sheets of bleached cotton duclf treated Wlth n'butyl in table nitroso N-methylcarbamate. The amount of the active insectic dal compound absorbed on the cotton cloth was determined gravimetrically, and on the basis of the Percent killed at end 40 volume of air in the closets the actual concentration in of hours p.p.m. of insecticide 1n the air was determined. Temsecticige perature in the closets was 75 F. After a 72-hour test Insecticide Q3333, Clothes Carpet interval, the closet was opened and counts were made of volume) lmoth beetles the number of insects killed. The exposed Petri dishes arvae containing the bacteria and fungi were removed and sterile Petri dish covers were replaced. Evidence of OHZNQN O COOC4H 2 8 $8 growth was observed after 24 hours incubation for bac- D-dichlorobemene 2g 22 teria and 5 days incubation for fungi. The results are None f 6 6 presented in the following table:

P.p.rn. of Clothes Oon- S2 EXAMPLE Iv statseat, as Tiiii' pita eat-z ms... methylperbeetle, m'ger 8p. coccus coZi zlla ty- The procedure described in Example III was carried out carbamate cent l s using as the insecticide n-propyl N-nitroso-N-methylcent carbamate with the same controls as in Example III. The results of the test are presented in the following Ffgifi jjjj 8 i; i; 5 table; 6.25 so 100 0 0 0 0 0 Norm-The sign indicates the presence of living microorganisms and the 0 indicates sterility.

Percent killed at end M72 As has been stated above the toxicants can be a l' d P.p.m. insechours PP 1e ticide (based in the samemanner in which toxicants have heretofore gfi g mothes Carpet been used. For example aerosols can be prepared commoth larvae eetles posed of about two parts by weight of liquid nitrosocarbamate toxicant and about 98 parts by weight of a 2.3 igg suitable propellant, such as Freon 12 or methyl chloride.

Furthermore, impregnated powders can be prepared by suitably admixing from about 5 to about 50% by XAMPLE V weight of a triosooarbamate toxicant with from about 95 to about 50 parts by weight of a suitable solid ad- The procedure described in Example III was carried sorbent carrier, such as pyrophillite, chalk, pyrethrum out using as the insecticide ethyl N-nitroso-N-ethylmare, diatomaeeous earth, walnut shell flour, and so carbamate with the same controls as in Example III. forth, 'as is well understood in the art. The particular 7 amounts of toxicant and solid carrier chosen will depend upon various factors, such as the ability of the solid carrier to absorb the toxicant and upon the final strength desired for the final composition.

Although specific embodiments of the invention have been described herein, it is intended that the appended claims not be limited thereto but be afforded the scope which shall include all modifications and equivalents thereof.

I claim:

1. A method for the preservation of a material normally subject to fungus and bacterial attack which comprises introducing into an atmosphere surrounding said material at least one nitrosocarbamate selected from the class CHa-IIT-fi-O R NO in an amount effective to prevent such attack, R being a radical selected from the group consisting of alkyl radicals having from 1 to 12 carbon atoms and monochloroalkyl radicals having from 2 to 12 carbon atoms.

2. The method of claim 1 in which R is n-butyl.

3. The method of claim 1 in which R is n-amyl.

4. The method of claim 1 in which R is n-hexyl.

5. The method of claim 1 wherein said material is selected from the group consisting of fruits and farm crops.

6. The method of combatting insects which comprises vaporizing in an enclosed area to be protected against attack by insects at least one nitrosocarbamate of the formula R-1\|l'-(|f-OR N0 0 where R is an alkyl radical having a number of carbon atoms, n, from 1 to 4, and R is an alkyl radical having a number of carbon atoms, 11', from 1 to 2, the amount of said nitrosocarba-mate vaporized being sufiicient to kill the insects. 7. The method as defined by claim 6 in which the sum of 2n+n is at least 5.

8. The nitrosocarbamates of the formula CH N(NO)COOR in which R is a normal alkyl hydrocarbon radical having from 4 to 6 carbon atoms. a

9. n-Butyl N-nitroso-N-methylcarbamate.

10. n-Amyl N-nitroso-N-methylcarbamate.

11. n-Hexyl N-nitroso-N-rnethylcarbamate.

References Cited in the file of this patent UNITED STATES PATENTS Deutschman et a1 May 4, 1954 OTHER REFERENCES UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,009,854 November 21 1961 William F. Russell It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6 line 71, for

"triosocarbamate" read nitrosocarbamate Signed and sealed this 10th day of April 1962.

(SEAL) Attest:

ERNEST W. SWIDER Commissioner of Patents 

1. A METHOD FOR THE PRESERVATION OF A MATERIAL NORMALLY SUBJECT TO FUNGUS AND BACTERIAL ATTACK WHICH COMPRISES INTRODUCING INTO AN ATMOSPHERE SURROUNDING SAID MATERIAL AT LEAST ONE NITROSOCARBAMATE SELECTED FROM THE CLASS 